1. Field of the Invention
The present invention relates generally to a portable testing device for reading small form-factor pluggable (SFP) or Mini-GBIC transceiver modules. In particular, the present invention relates to a system and method for a SFP Check that reads and decodes data from any type of SFP module to determine its SFP module-type.
2. Description of Related Art
With reference to FIGS. 1 and 2, a small form-factor pluggable (SFP) or Mini-GBIC transceiver module 10 is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. The SFP transceiver module 10 interfaces a network device mother board (e.g., for a switch, router, media converter or similar device) to a fiber optic or copper networking cable. SFP transceiver modules 10 are designed to support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards. The SFP module was designed after the GBIC interface, and allows greater port density (e.g., a greater number of transceivers per cm along the edge of a mother board) than the GBIC, which is why a SFP is also known as a mini-GBIC.
SFP transceiver modules 10 are available with a variety of different transmitter and receiver types, allowing users to select the appropriate transceiver 10 for each link to provide the optical transmission characteristics required over the available optical fiber type (e.g., multi-mode fiber or single-mode fiber). Optical SFP modules 10 are available in several different categories such as, for example:                850 nm 550 m multi-mode fiber (SX)        1310 nm 10 km single-mode fiber (LX)        1490 nm 10 km single-mode fiber (BS-D)        1550 nm [40 km (XD), 80 km (ZX), 120 km (EX or EZX)]        DWDM        
SFP transceivers modules 10 are also available with a copper cable interface, allowing a host device designed primarily for optical fiber communications to also communicate over unshielded twisted pair networking cable. There are also CWDM and single-fiber “bi-directional” (1310/1490 nm Upstream/Downstream) SFPs.
SFP transceivers modules 10 are commercially available with capability for data rates up to 4.25 Gbit/s. The standard is expanding to SFP+ which for supporting data rates up to 10.0 Gbit/s (that will include the data rates for 8 gigabit Fibre Channel, 10 GbE, and OTU2). SFP+ module versions for optics as well as copper are being introduced. In comparison to Xenpak, X2 or XFP type of modules, SFP+ modules leave some of the circuitry to be implemented on the host board instead of inside the module. The related Small Form Factor (SFF) transceiver is similar in size to the SFP, but is soldered to the host board as a pin through-hole device, rather than plugged into an edge-card socket.
The SFP transceiver module 10 is specified by a multi-source agreement (MSA) between competing manufacturers. One specification, for example, is the INF-8074i, which is sometimes referred to as the SFP MSA. SFP transceiver modules that are designed to this specification will allow the display of identification characteristics such as wavelength, type, range, vendor, part number, and date code. Another illustrative specification is SFF-8472, which provides specifications for a diagnostic monitoring interface for optical transceivers. SFP transceiver modules that are designed to this specification support the display of identification characteristics and diagnostic characteristics such as transmit and receive levels, laser bias current, voltage and temperature.
However, as a practical matter, the SFP transceiver modules 10 of some networking equipment manufacturers are not compatible with “generic” or MSA SFP transceiver modules because a check in the SPF module's firmware has been added that will only enable that vendor's own modules. The availability of incompatible SFP transceiver modules 10 makes replacement of a SPF transceiver module in an optical link difficult for a user (e.g., a user in the field repairing optical pathways) since replacement of a non-standard SPF transceiver module 10 with an incompatible transceiver module 10 will not suffice. Thus, a need exists for a portable SPF checking device into which a SFP transceiver modules 10 (e.g., a possible replacement SFP transceiver module) can be successively inserted to quickly and easily determine their respective vendors or vendor-specific specifications until the correct vendor's SFP transceiver module or otherwise compatible SFP transceiver module is located (e.g., from among many SFP transceiver modules carried by the user in the field) for use as a replacement.
Since the SFP transceiver module 10 is such a small optical device, there is little room on it for labeling. For example, a SFP transceiver module label 11 may indicate only a vendor name and/or a part number but no other characteristics such as laser power, transmit wavelength, transmit power, receiver sensitivity and other characteristics that would otherwise only be known if a data sheet for the SFP transceiver module were available. This is often not the case. In fact, data sheets are seldom available in the field and users often have dozens of SFP transceiver modules from different vendors in a box when doing repairs to optic pathways in the field and therefore have no way of knowing the respective SFP transceiver modules' characteristics without a reader or checker. The characteristics of SFP transceiver modules must be known in order to place the proper type of SFP transceiver module in an optical pathway under repair (e.g., some fiber pathways require a vendor-specific SFP transceiver module in order to function properly). Thus, a need exists for a reader or checker for SFP transceiver modules 10 that can quickly and easily determine an SFP transceiver module's characteristics. Some pattern test boards do exist for SFP transceiver modules such as the MSA transceiver testing device described in U.S. Patent Application Publication No. 2006/0189220 of Duval et al. Prior to putting MSA transceivers on the market for sale, transceivers are tested for quality control purposes. Since the types of the tested transceivers is already known, these pattern test boards are preconfigured to read only selected transceiver types. More specifically, they typically have several different sized cable connections for pattern and data rate testing of devices with known characteristics (e.g., an integrated pattern generator is used to verify the pattern of a known device to allow testing of devices to see if they meet specifications). Thus, the characteristics of the tested device are already known, or the tested device is known to be one of a small set of preselected types for which the pattern test board is preconfigured, and the characteristics of the tested device are merely being verified.
Further, some existing pattern test boards require an external power supply. Some of these test boards may also have no box or integrated housing and so they are merely intended for bench top checks only. See for, example, an evaluator board for testing a printed circuit board assembly device subcomponents disclosed in U.S. Pat. No. 7,024,329 and the illustrative test board 9 depicted in FIG. 2. Again, these devices do not determine and indicate to a user the type and characteristics of the tested component when its type is unknown.
A need therefore also exists for an SFP reader or checker for SFP transceiver modules or other SFP devices that can determine the characteristics of essentially any SFP module in the field (e.g., at a remote building telecommunications cabinet) as opposed to only at a bench top, and can determine these characteristics regardless of whether the SFP module type is known or not For example, a need exists for a SFP reader or checker that is portable and enclosed in a housing for use in the field, and has either an integrated power supply or can receive power for itself and a test device when the SFP reader or checker is connected to another device in the field. Further, a need exists for a portable SFP reader or checker that can read the characteristics of essentially any SFP transceiver, particularly when the SFP module type (e.g., vendor, part number and characteristics) is unknown, and conveniently display them for a user such as on a personal computer or laptop from which the SFP reader can also derive power for itself and the tested device.